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A titanic burp of protons from the Sun in 1859 appears to have temporarily weakened Earth's ozone layer, say scientists studying ice cores from Greenland.

Evidence of the massive radiation event comes from an excessive amount of ozone-related nitrates in the ice from that year.

The huge September 1859 solar flare appears to have gushed 6.5 times the protons of the largest flare seen by modern science, which was in 1989.

The researchers modelled the space storm using nitrate data from the ice and compared that with the modern event also detectable in the ice.

The researchers therefore estimateed that more than three times as much ozone was destroyed by the 1859 event than in the 1989 one.

Ozone is the gas that blocks ultraviolet-B (UV-B) light, which is particularly lethal to many life forms.

The discovery is a hint at just how nasty solar weather can get.

"The flare itself was observed directly," says researcher Assistant Professor Brian Thomas of Washburn University in Kansas of the 1859 event.

The flare was followed by a historic aurora light show and a geomagnetic storm that caused telegraph lines to spark and start fires.

In some places power surges created by the storm of charged solar particles blasting Earth's magnetic field made it possible to operate telegraph systems without added power, says space weather forecaster Dr Ron Zwickl, deputy director of the NOAA Space Environment Center in Colorado.

"Most people right now think that's the largest particle event," says Zwickl of the 1859 flare and storm of protons and other particles from the Sun.

The new research helps confirm that and zeroes-in on the effect the storm had on ozone worldwide.

Violent space weather

Figuring out the 1859 event has been the centre of study for many researchers because it seems to indicate that the Sun is capable of much more violent weather than we've seen or are prepared for, says Thomas.

Because much larger flares have been seen on nearby Sun-like stars, it's not impossible to imagine our Sun doing the same, Thomas explains.

The good news, adds Zwickl, is that those sorts of atmosphere-boiling solar events aren't very common as a star grows older. Lucky for us that the Sun is a middle-aged star.

It's fairly certain that over the history of the Earth, exceptional solar activity has led to ozone destruction and allowed harmful UV-B rays to reach the ground, which may even have ties to some extinction events, according to some researchers.

"We're not really sure what the upper limit of what the energy should be on these flares," Thomas says.

A paper using the ice core data to model the historic solar blast's effects on Earth's atmosphere, with Thomas as the lead author, appears in Geophysical Research Letters.

"We need to know more about how these flares occur," says Thomas. "This gives us impetus to keep looking."